Effects of the SNR of the signal replica in LMMSE-based filtering

A general issue in radar processing is amongst other ones to separate targets. Several advanced techniques have been developed to fulfill this objective, such as linear minimum mean square error based processing (LMMSE). Nevertheless they depend heavily on the signal replica known at the receiver, and exhibit degraded performance when this reference is not noise-free. And this is also true for the classic matched filter (MF). As such the replica used for correlation receiver can be described with a signal to noise ratio (SNR). The analysis of the effects is done for a multi-target scenario where targets are close enough for the sidelobes of a target to interfere with the main lobe of another target, and close-by weaker echos are also present. This paper shows some experimental and simulation results illustrating the effects when there is such a discrepancy between the echoing signal and the signal reference used in the processing. Also shown is the improvement when countermeasures to this problem are taken.